Cardinality Estimator

v1.0.0

HyperLogLog cardinality estimator — pick precision, estimate error margin, memory cost.

Precision bits (b = 4–18)

Result

HyperLogLog Configuration

Precision bits (b): 14
Registers (m):      16,384
Error rate:         ±0.81%
Memory:             64.0 KB (32-bit registers)

Common presets:
  b=10 → 1024 registers, ±3.25% error, 4 KB
  b=14 → 16384 registers, ±0.81% error, 64 KB  ← Redis default
  b=18 → 262144 registers, ±0.20% error, 1 MB

Redis: PFADD / PFCOUNT use b=14 (fixed)
Cardinality up to ~2^64 with this error rate.